Lower-surface micro-texturing on a NACA 4408: RANS CFD code and data

Code, meshing pipeline and numerical data for a Reynolds-averaged Navier–Stokes study of lower-surface groove and dimple micro-texturing on a NACA 4408 airfoil at Re = 5×10⁵, using OpenFOAM with the k-omega SST closure and Construct2D structured C-grids. Contents: the OpenFOAM case template, the sweep driver and near-wall texture-perturbation code, surface skin-friction and pressure extractions, and the polars for a smooth baseline and both textured cases. Two cautions for reusers. First, the reference smooth baseline is the y+ ~30 case. The y+ ~1 solutions are not converged and must not be used as a reference; see baseline_yp1_convergence_check.csv. Convergence on these meshes has to be judged from the full force-coefficient history, because linear-solver residuals reach 10⁻⁹ while the lift coefficient is still drifting. Second, absolute coefficients from the y+ ~30 meshes underpredict Cl by 11% and Cd by 20% against a refined wall-resolved baseline, so the texture results are differences between like-built cases rather than absolute predictions. The associated manuscript is not included in this deposit.